The field of the invention is filling containers generally, but more specifically the invention is concerned with a system and various features thereof as a subcombination of the system for filling molds for ceramic bottles.
Although an old art, slush molding is in extremely widespread use today for the manufacture of containers such as vases, jars, bottles and the like out of ceramic materials. In large production establishments potter's clay is mixed with water to provide a relatively free flowing slurry called slip that can be handled as a liquid. It is poured into molds which are permitted to remain quiescent for a time sufficient to have the slip immediately adjacent to interior surface of the mold set after which the still liquid center is poured out leaving a thin shell. This shell is permitted to dry sufficiently to become firm and removed from the mold. It thus becomes a hollow container after it is decorated and baked.
Many problems arise which must be solved in the factories where such processes are carried out. Foremost, of course, is the need for uniformity and high speed in production. The more manual operations required, the more expensive the product. The less uniform the product, the more rejections and breakage.
Solution of the problem of trying to achieve uniformity calls for filling the mold with the precise amount of slip and pouring the slip out of the molds at a time when a known volume of space will result due to the thickness of the remanent wall. Modern mold handling equipment permits of a large number of molds, for example ten or more, to be emptied simultaneously through the use of counterbalanced cradles, but the benefit of this type of equipment is to some extent offset by the requirement to fill the molds speedily and accurately. A workman moving a nozzle from mold to mold and filling by judgment cannot be expected to be as accurate as an automatic device. There is a certain amount of spillage, also. If he is careful, taking a bit more time to fill, the first-filled containers may end up with thicker walls than the last filled because slip sets at a very fast rate -- at least as it is used with a viscosity to promote fast setting for high speed production.
If one considers that the ceramic bottles are to carry an expensive commodity, such as for example, whiskey, a larger than required volume causes the filler to lose profits; a smaller than required volume causes the filler to have difficulty with the tax authorities. Accordingly, the manufacturing must be geared to the conditions of conservatism where the larger volume of the resulting container will be achieved in most cases, the consequences of less profits being less troublesome than not meeting the approval of tax authorities standards for required liquid volume.
An accurate filling system can satisfy the requirements of highest profits and least difficulty with tax authorities by producing uniform containers on a continuous basis. This can be done at high speed and quite reliably by the use of the invention.
In connection with the comment on reliability made above, a factory where ceramic containers are being made in large quantities is subject to a continuous atmosphere of clay dust, splashing and leaking of slip, etc. The dirt and clay settle on everything, the pouring of the liquid slip from the molds during the emptying thereof causes spray and flying droplets of slip in the vicinity of the molds, etc. As a result, any equipment which is used in the vicinity of the molding operation is subjected to this atmosphere and the splashing. Slip in large drops and splashes hardens quickly and is almost like cement. In dust form it clogs crevices and filters into electrical circuits to insulate contacts.
Accordingly, any equipment which is to be used for automatic filling must be robust, dust-resisting and must operate under adverse conditions described in order to be reliable. Without reliability, the benefits of automatic filling are lost because production speed and uniformity suffer.
The invention herein is believed to have solved the problems mentioned by providing a system which is rugged, reliable and flexible for different use requirements and which is capable of operating practically unattended in filling containers with liquid and achieving high uniformity at great speeds.
The system of the invention includes a carriage which has a filling nozzle associated therewith. The carriage is started down a line of containers on a track by the operator who can then leave the equipment and go to another system. The carriage moves to the first container, senses whether the container is in proper position, fills the container if all is well, moves to the next container and fills it if it is in proper condition, and so on. When the carriage reaches the end of the line it can be made to stop and sound a warning, or it can be made to return to its initial position without doing any filling or it can be made automatically to reverse and refill the containers, topping them up to compensate for evaporation, again sounding an alarm when it reaches its original position.
It may be noted here that in a practical system embodying the invention the timing device used by the molder to signify the precise setting time has a warning signal that advises when the molds are to be poured. The invention enables the molds to be filled and topped off in a reverse run in a time shorter than that required for setting; hence it is usually unnecessary for the carriage to sound an alarm either when the first pass has been made or when it reaches home.